It is clear that these membranes, whose material can break or become porous on aging, are elements which weaken the chamber, namely that they compromise the imperviousness of said chamber. Thus, there is a need to check the continuity of the material of the chamber.
Certain methods for controlling imperviousness are already known as are other techniques for checking the imperviousness of flexible or rubbery membranes, such as gloves. For example, it is possible to place the membrane against a weight able to conduct electricity and having a shape complementary to that of the membrane when in an idle position and bring an electrode near to the other side of the membrane. An electric current moves between the electrode and the weight if the membrane is not sealed. According to one variant of this method able to be used for gloves, a check is made to see if there is a electrostatic load loss between the wearer of the glove and an external electrode. But in all these methods, the membrane is detached from the support on which it is mounted, which is scarcely practical and inadequate for those membranes installed in front of the openings of the protection chambers. It is then necessary to test imperviousness, not only of the membrane, but of the mounting by which the membrane is connected to a collar or similar element of the chamber.